If you put a frog in a pot and turn up the temperature too quickly it will jump out, but if you slowly turn up the temperature by small increments it won't notice the difference and will stay until the water is eventually boiling.
This is all nonsense of course, but it serves as an apt metaphor of how our minds work.
There is a phenomenon called the 'just noticeable difference' or JND. The JND is the magnitude of a change before it becomes consciously detectible. If you sit in a dark room and somebody very slowly turns up the light, eventually the room will become fully lit without you noticing a change.
The JND has some important applications to marketing:
Sudden significant changes to logos, such as the Gap branding, are well documented. They were called out on poor design, but in my opinion, brands are shortcuts to decision-making and a sudden change revokes the ability of a logo to allow you to make a purchase decision quickly and automatically. Many brands have slowly and incrementally changed their logos, packaging or brand positioning in a structured way over time so that the brand moves with the times without alienating its customers.
Microsoft's move to Windows 8 was not what you'd call 'successful'. The sudden radical change in the way PC users interacted with their machines caused a huge backlash amongst the public. Instead of slowly and intuitively changing the interface, Microsoft implemented a major overhaul that left their frustrated customers desperately clicking on new and unfamiliar icons in the hope of getting on with their lives.
Changes to prices can also fall under the JND threshold, but sometimes you don't want them to. A reduction in price needs to be noticed. Likewise, an increase in product size at increased cost also needs to have the emphasis on the additional benefits. In these cases, it makes sense to increase emphasis on the positive changes through other marketing elements, such as signage.
Branding in advertising needs to be above the threshold of JND. We often see ads where the brand is the 'invisible gorilla' in the ad and goes unnoticed. But beware - an ad that puts the brand too far above this threshold can perform just as badly. Aim to be clear, but subtle.
In other words, know your JNDs and stop the frog from jumping out of the pot.
